IIT JEE , AIEEE Forum - Mathematics , Analytical Geometry

deep01

If the tangent at the point on the circle x²+y²+6x+6y=2 meets a straight line 5x-2y+6=0 at a point Q on the y-axis,then the length of PQ is:

(A)4 (B)2*(5^1/2)

(C)5 (D)3*(5^1/2)

aditya_arora04

Hi,

Look,

your equation : x²+y²+6x+6y-2 = 0

Now, the tangent meets the y-axis and the line at the same point. i.e point lies on 5x-2y+6=0 . Thus, the point is (0,3)

Now, length of the tangent = ( x1²+y1²+2gx1+2fy1+c )^1/2

here (x1,y1) is the point from which tangent is drawn

= ( 0²+3²+(6*0)+(6*3)-2 )^(1/2)

Solve it and you get the answer i.e 5.

So, answer is (c).

Please inform in case of problems.

rajat

yes he is ryt its c : 5

amar.gupta

good work aditya